读取行和命令行可以编程完成
command history and history/fc builtins
查看历史命令
csh-like history expansion
other new bash builtins: bind, command, compgen, complete, builtin,
declare/typeset, dirs, enable, fc, help,
history, logout, popd, pushd, disown, shopt,
printf
上边一堆新的bash内建命令。
exported functions
filename generation when using output redirection (command >a*)
重定向输出文件名的生成
POSIX.2-style globbing character classes
POSIX.2-style globbing equivalence classes
POSIX.2-style globbing collating symbols
POSIX.2风格的通配符类、等价类、通配符号
egrep-like extended pattern matching operators
case-insensitive pattern matching and globbing
不区分大小写的模式匹配和通配符
variable assignments preceding commands affect only that command,
even for builtins and functions
变量赋值前的命令只影响那个命令，包括内建命令和函数
posix mode
redirection to /dev/fd/N, /dev/stdin, /dev/stdout, /dev/stderr,
/dev/tcp/host/port, /dev/udp/host/port
debugger support, including `caller' builtin and new variables
调试支持，包括caller内建命令和新变量
RETURN trap
Things sh has that bash does not:
